Describe the changes that take place (i) around the rib cage (ii) diaphragm (iii) chest cavity, during inspiration. State the effect of these changes.


(1) During inspiration, the muscles, around the rib cage, contract, lifting the ribs upward and outward 

(2) Diaphragm contracts and becomes nearly flat sheet. 

(3) The chest cavity expands.

Effect – Air pressure inside the lungs falls below the pressure of the air outside the body. This creates a partial vacuum and so the air. from outside the body, rushes into the lungs.